Studies of hyaluronate metabolism in developing and regenerating tissues, and of the effect of this polysaccharide on chondrogenesis in vitro have led to an hypothesis that it prevents aggregation of mesenchymal cells, thus facilitating migration and delaying differentiation until its inhibitor effect is reversed and the molecule is removed by hyaluronidase action. To probe the biochemical basis of this inhibition by hyaluronate and to investigate the control of its effect, we will study (1) the binding to and interaction of hyaluronate with cell surfaces; (2) the effect of hyaluronate on cell differentiation, proliferation and movement; (3) the control of hyaluronate synthesis and degradation in vitro and vivo.